quartz block

A block of nearly pure quartz near the shore of Star Lake, Mt Madison NH.

Blocks like this (but mostly smaller) occur occassionally throughout the northern Presidential Range - you see them on the summit cone of Mt Washington in particular, where they're easily mistaken for snowfields. Breadloaf-sized quartz pieces are frequently used as the top stone in cairns for marking trails in the Presis.

"On two occasions I have been asked, 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."
--Charles Babbage